Method of producing hollow silica microparticles
A method of producing hollow silica microparticles that suppress whitening of a transparent coating film and show excellent abrasion resistance and adhesiveness. The method includes preparation of an organosol in which hollow silica microparticles are dispersed with the silica concentration of 1 to 70 W % and addition of a silane compound and an alkali catalyst to the organosol at a temperature in the range from 30° C. to 300° C. to react the silane compound to the hollow silica microparticles under the condition where a quantity of water against the added silica (the hollow silica microparticles) is in the range from 0.1 to 50 W %.
1. A method of producing hollow silica microparticles, comprising:
preparing an organosol in which raw hollow silica microparticles are dispersed with a silica concentration of 1 to 70 W %; and
adding a silane compound and an alkali catalyst to the organosol at a temperature in a range from 30° C. to 300° C. to react the silane compound with the raw hollow silica microparticles under a condition where a quantity of water against the raw hollow silica microparticles is in a range from 0.1 to 50 W %,
wherein the hollow silica microparticles have
an average particle diameter of 5 to 300 nm when measured by dynamic light scattering method,
a specific surface area of 50 to 1500 m 2 /g, and
an outer shell in which cavities are formed,
the hollow silica microparticles lose a weight by 1.0 W % or more at a temperature in a range from 200° C. to 500° C. when measured by thermogravimetry (TG),
a quantity of the silane compound added to the organosol is in a range from 1 to 50weight portions against 100 weight portions of the raw hollow silica microparticles, and
a quantity of the alkali catalyst added to the organosol is in a range from 20 to 2,000 ppm against the organosol.
2. The method of producing hollow silica microparticles according to claim 1 , wherein the hollow silica microparticles have a positive DTA peak when measured by differential thermogravimetric analysis (DTA) at a temperature in a range from 200° C. to 500° C.
3. The method of producing hollow silica microparticles according to claim 1 , wherein the hollow silica microparticles have an organic group directly bonded to a silicon atom on a surface thereof.
4. The method of producing hollow silica microparticles according to claim 3 , wherein the organic group is at least one selected from the group consisting of saturated or unsaturated hydrocarbon groups having 1 to 18 carbon atoms and halogenated hydrocarbon groups having 1 to 18 carbon atoms.
5. The method of producing hollow silica microparticles according to claim 4 , wherein the hollow silica microparticles have the organic group expressed by general formula (1) or general formula (2), and the hollow silica microparticles lose the weight by 1.5 W % or more at the temperature in the range from 200° C. to 500° C. when measured by thermogravimetry (TG),
—R—OC(═O)CCH 3 ═CH 2 (1)
—R—OC(═O)CH═CH 2 (2),
where R is a bivalent hydrocarbon group having 1 to 12 carbon atoms.
6. The method of producing hollow silica microparticles according to claim 4 , wherein the hollow silica microparticles have the organic group expressed by general formula (3),
—R—C n F a H b (3),
where
a+b= 2 n+ 1,
n is an integer of 1 to 3, and
R is a bivalent hydrocarbon group having 1 to 12 carbon atoms.
7. A method of producing hollow silica microparticles, comprising:
preparing an organosol with a silica concentration of 1 to 70 W % in which raw hollow silica microparticles are dispersed in an organic solvent; and
adding a silane compound and/or a multifunctional acrylic acid ester resin having a, and an alkali catalyst to the organosol to react the silane compound with the raw hollow silica microparticles under a condition that a quantity of water is in a range from 0.1 to 50 W % against a quantity of silica blended therein,
wherein the hollow silica microparticles have
an average particle diameter of 5 to 300 nm when measured by dynamic light scattering method,
a specific surface area of 50 to 1500 m 2 /g, and
an outer shell in which cavities are formed,
the hollow silica microparticles lose a weight by 1.0 W % or more at a temperature in a range from 200° C. to 500° C. when measured by thermogravimetry (TG),
a quantity of the silane compound added to the organosol is in a range from 1 to 50weight portions against 100 weight portions of the raw hollow silica microparticles, and
a quantity of the alkali catalyst added to the organosol is in a range from 20 to 2,000 ppm against the organosol.
8. The method of producing hollow silica microparticles according to claim 7 , wherein the hollow silica microparticles have a positive DTA peak when measured by differential thermogravimetric analysis (DTA) at a temperature in a range from 200° C. to 500° C.
9. The method of producing hollow silica microparticles according to claim 7 , wherein the hollow silica microparticles have an organic group directly bonded to a silicon atom on a surface thereof.
10. The method of producing hollow silica microparticles according to claim 9 , wherein the organic group is at least one selected from the group consisting of saturated or unsaturated hydrocarbon groups having 1 to 18 carbon atoms and halogenated hydrocarbon groups having 1 to 18 carbon atoms.
11. The method of producing hollow silica microparticles according to claim 10 , wherein the hollow silica microparticles have the organic group expressed by general formula (1) or general formula (2), and the hollow silica microparticles lose the weight by 1.5 W % or more at the temperature in the range from 200° C. to 500° C. when measured by thermogravimetry (TG),
—R—OC(═O)CCH 3 ═CH 2 (1)
—R—OC(═O)CH═CH 2 (2),
where R is a bivalent hydrocarbon group having 1 to 12 carbon atoms.
12. The method of producing hollow silica microparticles according to claim 10 , wherein the hollow silica microparticles have the organic group expressed by general formula (3),
—R—C n F a H b (3),
where
a+b= 2 n+ 1,
n is an integer of 1 to 3, and
R is a bivalent hydrocarbon group having 1 to 12 carbon atoms.
13. The method of producing hollow silica microparticles according to claim 7 , wherein
the hollow silica microparticles have
an organic group directly bonded to a silicon atom on a surface thereof, and
surface charge (QA) in a range from 5 to 20μeq/g, and
a positive DTA peak at a temperature in a range from 200° C. to 500 ° C. when measured by differential thermogravimetric analysis (DTA).
14. A method of producing hollow silica microparticles, comprising:
preparing an organosol in which raw hollow silica microparticles are dispersed with a silica concentration of 1 to 70 W %; and
adding a silane compound and an alkali catalyst to the organosol at a temperature in a range from 30° C. to 300° C. to initiate a hydrolysis reaction between the silane compound and a silanol group on surfaces of the raw hollow silica microparticles under a condition where a quantity of water against the raw hollow silica microparticles is in a range from 0.1 to 50 W %, thereby bonding an organosilyl group to the surfaces of the raw hollow silica microparticles,
wherein the hollow silica microparticles have
an average particle diameter of 5 to 300 nm when measured by dynamic light scattering method,
a specific surface area of 50 to 1500 m 2 /g, and
an outer shell in which cavities are formed,
the hollow silica microparticles lose a weight by 1.0 W % or more at a temperature in a range from 200° C. to 500° C. when measured by thermogravimetry (TG),
a quantity of the silane compound added to the organosol is in a range from 1 to 50weight portions against 100 weight portions of the raw hollow silica microparticles, and
a quantity of the alkali catalyst added to the organosol is in a range from 20 to 2,000 ppm against the organosol.
15. The method of producing hollow silica microparticles according to claim 14 , wherein the organosilyl group includes a monoorganosilyl group, a diorganosilyl group, or a triorganosilyl group.